D&#39;arsonval relay



July 13, 1943 A. J. McMAsTER 2,324,265l

' DARSONVAL RELAY Filed July 19, 11940 NVENTOR.

Patented July 13, 1943 DARSONVAL RELAY Archie J. McMaster, HighlandPark, Ill., assigner to G-M Laboratories, Inc., Chicago, Ill., acorporation of Illinois Application July 19, 1940, Serial No. 346,272

12 Claims.

My invention relates to electrical relays. It relates more in particularto a sensitive relay of the DArsonval type.

The DArsonval relay makes use of a DArsonval meter apparatus, whichincludes a coil situated in a magnetic field and mounted to have arotary motion about an axis substantially perpendicular to the directionof the lines of force of the magnetic eld, for example, the eld of apermanent magnet. When a current flows through the coil, the coilrotates in response to reaction between its field and the iield of thepermanent magnet, the tendency being for the coil to move into aposition where its plane cuts straight across the lines of magneticforce, the direction of movement, of course, depending upon thedirection of the current in the coil. Spring means are used to hold thecoil in zero position when no current is iiowing. The coil, therefore,rotates in response to the passage of an electric current therethroughand returns to its zero or rest position when this current isinterrupted.

When the DArsonval movement is used in relays, the moving coil, or aportion of an assembly of which the moving coil forms a part, carries acontact, and a second or stationary contact is engaged by the movablecontact when the current in the coil is sufiicient to move it againstthe torque of the spring a sufficient distance. The two contacts, one ofwhich is carried by the movable coil, usually operate auxiliaryequipment, so that the ordinary DArsonval relay involves at least twocircuits, one flowing through the meter coil and the other supplyingcurrent to the auxiliary apparatus.

DArsonval relays are used quite extensively because of certain inherentadvantages, among the most important being relatively high sensitivityas compared to relays of more conventional type employing a stationarycoil, pole piece and movable armature. Disadvantages which have beenfound in DArsonval relays relate almost entirely to the difficulty ofobtaining good, low resistance contact at all times between thestationary and moving contact members which control the auxiliaryapparatus. Because of the relatively low contact pressure, the greatestdifiiculty is probably due to the presence of surface lms which are notcompletely penetrated when the contacts close mechanically, andtherefore offer a high resistance to the circuit controlled by thecontacts. This is particularly true when the contacts are relativelyrigid and have substantially no flexing action when they meet. In

the design of DArsonval relays, therefore, attempts have been made toprovide a iiexible contact, usually on the rotating or moving contactmember. The structures employed have not been fully satisfactory formany reasons known in the art, and it is not unusual to find instanceswhere very rm mechanical contact has been made and yet there is afailure to make electrical contact.

The principal object of the present invention is the provision of animproved sensitive relay.

Another object is to overcome problems and disadvantages which haveheretofore been encountered in the so-called DArsonval type of relay.

A further object is the provision of a DArsonval type of relay, soconstructed and arranged that good electrical contact will be made atall times and wherein there will be no cohesion or sticking of thecontacts due to Welding, friction, binding action of surface films, orthe like.

Other specific objects and features of the invention will be apparentfrom the following description taken with the accompanying drawing,wherein Fig. 1 is a plan view showing one embodiment of the relay of mypresent invention, the view being approximately twice full scale;

Fig. 2 is an elevational View looking along the front edge of the relayshown in Fig. 1;

Fig. 3 is a sectional view through the pivots of the moving coil, thesection being taken on the line 3-3 of Fig. 1 looking in the directionof the arrows, and the View being about double the scale of Fig. 1;

Fig. 4 is an enlarged plan sectional view taken on the line 4 4 of Fig.2 looking in the direction of the arrows and illustrating the relativepositions of the stationary and moving contacts when the coil is in zeroposition; and

Fig. 5 is aview similar to Fig. 4 and illustrating positions of theparts when electrical engagement has been made between the movable andstationary contact members.

In general, my invention provides a normally stationary contact, in theform of a wire, springpressed against a stop whereby to fix itsposition. This wire is exed in response to engagement by a wire at rightangles to it carried by the moving coil so that actually it is notliterally stationary. For the purpose of differentiating it from themoving contact member carried by the coil, however, I have referred toit as a stationary contact member and throughout this specification andin the claims shall refer to it as the stationary contact member. Itcorresponds in its function with the normally stationary contact memberon this type of instrument.

The wire which comprises the stationary contact member may be relativelylong and straight so as to flex along its entire length from the pointof its support. Preferably, however, it comprises a straight portion anda helical spring portion, thus permitting its being carried in a muchsmaller space than would be required if a single, relatively long,straight wire were used in its place. The use of a stationary contact ofthis character, having a coil spring portion, also permits using a wirewhich is relatively large in diameter, thereby avoiding excessive localheating due to sparking and a consequent welding' between the twocontacting wires; It is obvious that, with a highly sensitive instrumenthaving threaded radially through the core, engages the bearing member2L! to adjust it to a position to provide the proper amount of frictionon the pivots.

To return the coil assembly to Zero position after actuation, relativelylight helical springs 21 and 28 are provided at top and bottom, in eachinstance one end of the helical spring being secured to the coilassembly and the other end being secured to a stationary portion.Looking at spring 28, it will be seen that one end thereof is secured tothe lower end of the mounting strip Id and the other end is secured to asmall tab 29 projecting downwardly from a right angular portion of thesame member which is secured to the bottom lof the moving coil assemblyso as to move it. It will simplify explaining the mountlow torque, arelatively heavy wire would have to be quite long in order to obtain therequisite flexing action. i

The wire comprising the stationary contact is so adjusted that, if itwerenot constrained .by a stop, it would spring a substantial distancein the kdirection of the moving contact member. When held in its properplace, it'exerts a positive pressure against its stop, preferablyagainst the smooth inside surface of a U-shaped clip, and its positionis, therefore, denite and permanent. This prevents the stationarycontact member from vibrating as it otherwise would and prevents itsposition becoming changed due to the relief of strains which might haveoccurred in its fabrication.

The movable Contact member, as previously noted, is a wire of alloymaterial mounted to engage the wire comprising the stationary contactmember at right angles to it, thereby forming a point to point contactwith comparatively high unit pressure considering the relatively lowtorque exerted by the rotating coil. The moving contact member andstationary contact member are so constructed and arranged, as will bepointed out hereinafter, that there is a decided wiping action when theycome into mutual engagement. The self-cleaning action which-results fromthe wiping of the contacts is very 'effective in breaking through anysurface lm which may be present and in maintaining the contacts in aclean condition at the point of engagement-in short. the wiping actionis very important in overcoming high contact-resistance.

While the invention may have various embodiments, the drawing shows thefeatures discussed in a combination which has been found very effectiveinactual commercial operation.v Looking at the drawing, a permanentmagnet Il! is provided having soft iron pole pieces II and I2 be-` tweenwhich the moving coil of the instrument is mounted, The constructionutilizes a nonmagnetic mounting yoke I3 having a downwardly extendingmounting clip Ill. A core I6 is secured to the mounting strip I4 by asmall screw Il, and, in addition to its usual magnetic function, thecore IB acts as a support for pivotally mounting the coil. The coilproper I8, consisting of a suitable number of turns of wire, is wound ona rectangular yoke I9 which carries two pivot points 2| and 22. Thesepivot points engage in depressions in bearing members 23' and 24 carriedaxially within the core I6. Any suitable bearing surfaces may beprovided for the pivot points such as the usual jewels employed in this.general type of moving coil instrument. 'Ihe bearing member 24 isrelatively loose within the core I6, and a set screw 26,

ing for the spring 21 if some of the related parts are first described.

' Secured to the outside of the coil assembly at the top thereof is astrip 3| havinga portion 32 extending downwardly in front' of the coreI6 and serving as a counterbalance for the moving coil, and a movablecontact carrying member 33 having mounted at its end a vertical wire 34which comprises the movable contact member.

Secured above the core I3 by spacers 35 are a pair of transverseinsulating and mounting strips 37. These carry between them awasher-like spring supporting member 38 and a downwardly extendingspring mounting portion 39. The strip 3| has an upturned portion 4I. Thehelical return spring 21 has its outside end secured to the member 39and its inside end to the member 4I.

Stacked with respect to the strips 31 and the washer-like member 38 areadditional members which need not be described in detail butwhichinclude a stationary contact carrying member A2. These stacked membersare held in assembly by a hollow rivetvLlB, and, in addition to havingthe supporting function already noted, this assembly provides'means4 forestablishingsuitable circuits which may Vary depending upon the specificconstruction'and use to which the'instrument is to be put, but Whichneed" not be considered so far as the present invention is concerned.

The stationary contact carrying member G2 is shown in detail in Figs. iand 5, and includes a projection 4.43 and a projecting U-shaped portion46 which, in 'a manner to be described, acts as a stopY for thestationary contact member. Also secured to the member 62 and projectingupwardly therefrom is a headed stud A stationary contact member'B, inthe form of a spring wire, has one end secured by suitable means, suchas welding, to the projection 154, Ia portion .49 extending to the studil?, and a coil portion 5i. The extending end of the stationary contactmember 3 is free, but a short wire 52, secured across the legs of theU-shaped projection llt, functions to maintain the movable contactmember within the area defined by the U.

My invention is concerned substantially entirely with the constructionand arrangement of the Contact members, although the moving coil andassociated parts have been shown and described so that those skilled inthe art will understand how the contact members are mounted andoperated. Since the circuits involved may vary, I do not deem itessential to consider either the manner in which the current isdelivered to the coil nor the manner in which the contact members 34 andi8 may comprise a part of a circuit includingauxiliary apparatus. Theseare conventional matters. I wish, however,

to pointout certain features .with respect to the -construction andoperation of the relay so far as the contacts 34 and 48 'are involved.

Ina relay of the type shown, the initial contact-may be made on lessthan one microwatt of energy. This figure is illustrative and, ofcourse, not limiting. The result is that the torque is relatively lowand the energy lavailable to establish and maintain adequate electricalcontact is limited. I have already pointed out that the stop,

lin the form of a U-shaped clip in the drawing,

definitely positions the sor-called stationary contact member 48, butthat the spring action embodied in this Contact member is such as tocause it to move about the stud 41 as a pivot a substanltial distance ifit were released from its stop.

The result is that, while the stationary contact member 48 is resilientwith an advantage which will be pointed out, it is not subject tovibration as an unsupported wire would be and, even though' the tensionon the spring might be relieved considerably, it will always be in thesame position and the operating voltage value of the relay .effective toclose the Contacts will remain substantially uniform 'during the life efthe instrument. It will be noted, by comparing the f shape of the member46 as seen in Fig. 3 and the cross section thereof as shown in Fig. 4,that it presents a smooth surface to the wire forming the stationarycontact, and there are no rough edges on which it might catch and beprevented from returning to its fixed stop position.

The wires comprising the contact members may be formed of variousmaterials, but preferably the material used in one contact member isdifferent g from the material used in the other. I have found thatsilver palladium wire is an excellent material for the fabrication ofthe contact member 48, and the contact .member 34- may be formed ofplatinum iridium or other relatively harder contact material. The wipingand resulting cleaning action is more satisfactory when the materialsare different than when the same material is used in both contacts.

By employing wires placed at right angles to each other, a point topoint contact is obtained, thereby producing a relatively strong unitpressure at the point of contact. Whatever wiping action takes place,the point to point contact is maintained. As will be explained more indetail, the support for the stationary contact member is not along theradius line of the moving contact member, and the result is that, whenthe wires engage, there is a motion of the moving contact member 'alongthe stationary contact member as the latter is deflected slightly,thereby creating the wiping action to which reference has been made. Itis essential, therefore, that the stationary contact member be soconstructed and arranged that it will be deflected an appreciable amountin order to make possible this sliding action.

Keeping in mind that the energy available for deecting the wirecomprising the stationary contact member is very small, it follows thatthis wire would have to be very small in cross section or long enough sothat the small force available could move it. If the wire is too smallin cross section, then there is insufficient metal present to carry awaythe heat resulting from the arcing on breaking contact, and welding willoccur. If the wire is made of sufciently large cross section to avoid'the possibility of welding due to arcing, then it must be longer thanordinary design principles rwill usually permit. By employing astraightsection with Vav spring coil portion intersupport, the sameeffect is obtained as if the wire vwere very much longer. ABy the useof'this construction,'I may employ a wire wherein the cross section`throughout is not uniform, that is to say, the cross section along thestraight portion engaged by the moving contact member may be somewhatgreaterthan the cross section of the remaining portion of the wire.rlhis may be accomplished by employing Va separate sleeve, by securingtogether two different types of wire, or in other ways familiar toabricators of metals. This arrangement has the added advantage ofpermitting the use of two different types of metals, one type'suitablefor a contact 'and another type more suitable so far as spring action,conductivity and the like are concerned.

I wish now'to refer more in detail to the construction` employed forsecuring the wiping action. Looking at Figs. 1 and 4, it will be notedthat the' effective pivot point of the moving contact member 34 may beidentified by the reference character A which corresponds to the axisabout which the coil I8 rotates. For convenience, we may assume that thepoint B, corresponding to the aXis of Stud 4l, is a point about whichthe stationary contact 48 pivots in response to being moved byengagement of the moving contact member 34. If We compare Figs. 4 and 5,we

vwill see that,-in the unactuated position shown in Fig. 4, the contact48 is against the stop 4S, but, in Fig. 5, it has been engaged by themoving contact 34 and forced in a clockwise direction away from the stop45. Some of this movement is due toa slight flexing of the straightportion 48, but the greater portion of this movement is due to movementat the coil spring portion 5l. For our purpose, however, in explainingthe construction and arrangement, we may assume that this movement ofthe stationary Contact member 48 is about the point B.

By eXamining-the'i-lgures which show the parts in plan view, it willatonce be apparent that, if a line is drawn from the point A to thepoint of initial engagement of the two contact members, andanotherline'is drawn from the point B to this point of engagement, there willbe a subtending angle which will'indicate the extent to which the pointB is removed from the radius of the circle defined by thearc over whichthe moving contact member is actuated about its axis A. If we now takethe position at which the parts come to rest after full actuation anddraw lines 'from the points A and B to the point of ultimate engagementof the two contact members, wewill nd that this angle is 'smaller thanviously referred to. kDuring the entire movement from the position ofthe parts shown in Fig. 4 to the positionof the broken line C in Fig. 5(if the parts were to move this far), there would be a wiping action ofthe moving Contact member 34 along the stationary contact member 48. Itis desirable that the wiping action be as great as possible, but thoseskilled in the art will see about 75 degrees.

that' there are other factors which prevent the use of a design whichwill permit extreme wiping action such as that suggested. The point israised, however, to illustrate that, ifV the point B should be solocated with respect to the point A that movement of the moving contactmember 34 would carry the stationary contact 48 past the point A (thatis, beyond a point where the point B would coincide with the radiusline), there would still be a wiping action, but the angle from thepoint A to the point of engagement between the contact members and toYthe point B would then be a negative angle. While this is permitted anda wiping action would definitely occur, I prefer, in the design, tomaintain the angle referred to positive when the parts have reachedtheir extreme of movement.

I have determined that the angle from the point A to the vpoint ofinitial Contact between the members 34 and 48, and then to the point B,

should be at least approximately 25 degrees. This angle, however, may begreater, in theory very much greater, because, in general, the greaterthe angle the greater the wiping action. There are other factorsinvolved, however, including the friction between the'two wires when theangle is relatively great, cohesion of the wires due to thin films, andthe welding action which may occur. Concerning the latter, welding atthe break, welding during wiping due to spot on the wire of lowconductivity and possible arcing, and welding at the make due tobouncing are factors to consider. After extensive tests and analysis ofthe factors involved, I have determined that this angle defined by theposition of the points A and B and the point of initial contact betweenthe contact members should not be greater than A very desirable angle isapproximately 45 degrees with plus or minus 20 degrees suitable if themost important advantages of my invention are to be secured.

In connection with the practice of my present invention, I wish to pointout that the circuit shown in myprior Patent 2,113,737 may be used togreat advantage with my present invention. When this circuit isemployed, it is only necessary that the two wires just make contact, andthe extra energy resulting from the use of the energy transfer circuitcauses a substantial further movement of the contacts and, of course, adefinite wipe over the maximum range permitted by the design of theinstrument. When the locking-in circuit forming a part of the energytransfer circuit, as shown in my prior patent, is opened, the storedenergy of the stationary contact member accelerates the return movementof the moving contact member 34, and acts to prevent sticking of themoving contact member to the stationary contact. I'have found that, evenwhen I applied grease films for test purposes, sticking did not occur. Iwish to call attention to the fact, however, that, due to the initialspring tension in the contact member 48, which isa major force ascompared to the added tension resulting from delecting it duringoperation of the meter, this pronounced return movement takes place atall times if enough torque has been applied to the moving contactassembly to take the stationary contact member 48 away from its stop 46.It is at least in part due to the energy stored in the contact member 48that I am able to employ as large an angle between the points A and B asthat described.

Those skilled in the art will appreciate that the structure, size,purpose and general arrangement of parts of my improved relay may bemodified quite extensively while still obtaining the very desirableadvantages-which the invention makes possible. It is obvious, forexample, that the two contact wires may be caused to engage each otherat right angles and still not havev the conformation and relationshipshown in the drawing. The normally movable contact, for example, couldlie in a horizontal plane and the normally stationary contact in avertical plane. yI'his would modify the force of contact when thecontacting wires slide relatively to each other, but, under somecircumstances, would not be objectionable, particularly if the point ofengagement moved closer to the axis of the movable contact member aswiping occurred.

Throughout the specicatiori,Y where I refer to wire contact, it shouldbe understood that the `significant criteria is not the circular crosssection normally found in wire, but rather the provision of acylindrical or partly cylindrical engaging surface affording asubstantially point-topoint contact betwen the contact members whilestill permitting free sliding action. It is at once apparent, therefore,that, if the contacts are of solid cross section, it is not essentialthat they be of circular cross section. For this reason, the contactmembers may be hollow, as in a tube, flat or ribbon-like in crosssection, V-shape, the shape 'which is assumed by a partially attenedsolid circular wire, or similar shape which will provide, at the pointof engagement, the same general kind of engagement as that occurringbetween relatively small cross section Wires engaging at right angles toeach other.

I wish to point out further that,in the claims, I refer to the coil asbeing on a vertical axis, in order more clearly to denne the relativepositions of the parts. It should be'well understood by those skilled inthe art, however, that the instrument may be mounted insubstantially'any position, and references to fixed positions of theparts in the claims are not a limitation except in so far as therelative positions of the -parts are defined.

The invention is defined by the appended claims when interpreted in thelight of the specification.

What I claim as new and desire to protect by Letters Patent of theUnited States is:

l.. In a. DArsonval relay, a DArsonval meter apparatus including a coilassembly rotatable about a vertical axis, a movable contact membercarried by the coil assembly comprising a wire of relatively small crosssection disposed in a plane substantially parallel to the axis of thecoil assembly, but spaced therefrom, and a. normally stationary contactmember in the ferm of a wire disposed in the path of saidl movablecontact member and lying in a plane at right angles thereto so that saidcontact members engage each other in point to point relation, saidnormally stationary contact member being supported at a point spacedfrom a line drawn at any point through the axis of rotation of the coilassembly, and being so constructed and arranged as to flex between thepoint of its support and the point of engagement by the movable contactmember, the angle formed by drawing two lines, one from said axis andone from the point of support of the normally stationary contact member,each line extending to the point of initial engagement between thecontact members, being not less' than about 25 degrees nor more thanabout 75 degrees.

2. In a DArsonval relay, a DArsonval meter apparatus including a coilassembly rotatable about a vertical axis, a movable contact membercarried by the coil assembly comprising a Wire of relatively small crosssection disposed in av plane substantially parallel to the axis of thecoil assembly, but spaced therefrom, and a normally stationary contactmember in the form of a wire disposed in the path of said movablecontact member and lying in a plane at right angles thereto so that saidcontact members engage each other in point to point relation, saidnormally stationary contact member being supported at a point spacedfrom a line drawn at any point through the axis of rotation of the coilassembly, and being so constructed and arranged as to flex between thepoint of its support and the point of engagement by the movable Contactmember, the angle formed by drawing two lines, one from said axis andone from the point of support of the normally stationary contact member,each line extending to the point of initial engagement between thecontact members, being about 45 degrees.

3. In a DArsonval relay, DArsonval meter apparatus including a coilassembly rotatable about a vertical axis, a vertical contact wirecarried by said assembly and rotatable therewith, and a second contactwire having a straight portion lying in the path of said verticalContact wire, and a coil spring portion disposed around a stationarystud as a support, said straight portion lying in a plane at rightangles to the plane of said vertical Contact wire.

4. In a DArsonval relay, DArsonval meter apparatus including a coilassembly rotatable about a vertical axis, a vertical Contact wirecarried by said assembly and rotatable therewith, and a second contactwire having a straight portion lying in the path of said verticalcontact wire, and a coil spring portion disposed around a stationarystud as a support, said straight portion lying in a plane at rightangles to the plane of said vertical contact wire, said stud beingspaced from a radius line of a circle dened by the arc over which saidvertical contact wire travels.

5. In a DArsonval relay, DArsonval meter apparatus including a coilassembly rotatable about a vertical axis, a vertical Contact wirecarried by said assembly and rotatable therewith, and a second contactwire having a straight portion lying in the path of said verticalcontact wire, and a coil spring portion disposed around a stationarystud as a support, said straight portion lying in a plane at rightangles to the plane of said vertical contact wire, said straight portionand a radius line running from the point of initial engagement of saidcontact members and passing through the axis of rotation of said coilassembly defining an angle.

6. In a DArsonval relay, DArsonval meter apparatus including a coilassembly rotatable about a vertical axis, a vertical contact wirecarried by said assembly and rotatable therewith, and a second contactwire having a straight portion lying in the path of said verticalcontact wire, and a coil spring portion disposed around a stationarystud as a support, said straight portion lying in a plane at rightangles to the plane of said vertical contact wire, said straight portionand a radius line running from the point of initia1 engagement of saidcontact members and passing through the axis of rotation of said coilassembly denning an angle of about 45 degrees.

7. In s, DArsonval relay, DArsonval meter apparatus including a coilassembly rotatable about a vertical axis, a vertical contact wirecarried by said assembly and rotatable therewith, and a second contactwire havinga straight portion lying in the path of said vertical contactwire, and a coil spring portion disposed around a staitionary stud as asupport, said straight portion 1ying in a plane at right angles to theplane of said vertical contact wire, said straight portion and a radiusline running from the point of initial engagement of said contactmembers and passing through the axis of rotation of said coil assemblydening an angle of between about 25 degrees and about 75 degrees.

3. In a DArsonval relay, DArsonval meter apparatus including a coilassembly rotatable about a vertical axis, a Contact wire carried by saidassembly and rotatable therewith, a second coniact wire having astraight portion lying in the path of said vertical contact wire in aplane at right angles to the plane of said vertical Contact Wire andadapted to be flexed in response to continued movement after engagementhas been made, said second contact wire being springpressed in adirection opposite to that in which it is moved by said vertical contactwire, and stop means to limit the movement of said second contact wirewhereby its position when engaged by the vertical contact wire is fixed.

9. A relay as defined in claim 8 wherein said stop comprises a U-shapedyoke.

l0. In a DArsonval relay, a stationary contact in the form of a wirehaving a straight portion, springs means urging said straight portion inone direction about a pivot point, stop means limiting the movement ofsaid straight portion whereby it is normally held spring-pressed in aiixed position against said stop, and a movable Contact member having astraight wire portion disposed in a plane at right angles to the planeof the straight wire portion of the stationary contact, and adapted onmovement to engage said straight portion at a point to move it about itspivot against the force of said spring means.

l1. In a DArsonval relay, a stationary contact in the form of a wirehaving a straight portion,

spring means urging said straight portion in one direction about a pivotpoint, stop means limiting the movement oi said straight portion wherebyit is normally held spring-pressed in a xed position against said stop,and a movable contact member having a straight wire portion disposed ina plane at right angles to the plane of the straight wire portion of thestationary contact, and adapted on movement to engage said straightportion at a point to move it about its pivot against the force oi saidspring means, the said contacts being so constructed and arranged that,on continued movement of the movable contact after initial engagement ofthe said straight portion, said contacts slide relatively to each otherand produce a distinct wiping action at the points of engagement.

l2. In a DArsonval relay, a DArsonval meter apparatus including a coilassembly rotatable about a vertical axis, a movable contact membercarried by the coil assembly comprising a member having a contactsurface of relatively small arcuate cross section disposed in a planesubstantially parallel to the axis of the coil assembly, but spacedtherefrom, and a normally stationary Contact member in the form of amember having a contact portion of relatively small arcuate crosssection disposed in the path of the movable contact member and havingits contact surface disposed at right angles to the contact ofengagement by the movable contact member, whereby said normallystationary contact member may relax from said stop position after er1-gagement and cause a wiping action between 5 the Contact members.

ARCI-IIE J. MCMASTER.

